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Physiology and Biochemistry

Influence of CO₂ Uptake of Barley Leaves on Incubation Period of Powdery Mildew Under Different Light Intensities. H. J. Aust, Phytopathologie und Angewandte Entomologie des Tropeninstitutes, Justus-Liebig-Universitãt, D 6300 Giessen, Germany; W. Domes(2), and J. Kranz(3). (2)Department of Botany, Philipps Universitãt, D 3550 Marburg, Germany; (3)Phytopathologie and Angewandte Entomologie des Tropeninstitutes, Justus-Liebig-Universitãt, D 6300 Giessen, Germany. Phytopathology 67:1469-1472. Accepted for publication 27 May 1977. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-1469.

Uptake of CO₂ was measured on both sides of barley leaves following inoculation of the leaves with Erysiphe graminis f. sp. hordei. The CO₂ uptake increased during infection whereas it decreased during incubation and sporulation. Disease development had little influence on the gas exchange through the upper epidermis since 82% of the CO₂ passed through the lower epidermis in all treatments. However, a positive correlation (r = 0.992) was found between light intensities, length of incubation period, and CO₂ uptake by infected leaves.